The Kinslayer Wars

Description for THE KINSLAYER WARS by Douglas Niles:

The leader of the Wildrunners, Kith-Kanan, commits the ultimate heresy and falls in love with a human of intriguing background. His twin brother, the firstborn ruler of all Silvanesti elves, Sithas, declares war on the Ergothians, and Kith-Kanan must choose sides. Nobly, he fights alongside his proud race in the terrible Kinslayer Wars. But when the historic Swordsheath Scroll is signed, Kith-Kanan and his followers are forced into a tragic exile.

The Elven Nations Trilogy Volume Two.